[cfe-dev] [PATCH] C++ nested-name-specifier (Parser)

Eli Friedman eli.friedman at gmail.com
Fri Aug 1 15:43:22 PDT 2008

On Fri, Aug 1, 2008 at 12:39 PM, Argiris Kirtzidis <akyrtzi at gmail.com> wrote:
> Hi,
> For the next chapter of the C++ support saga, I've implemented
> nested-name-specifier support ("foo::bar::").

Hmm, I don't have any low-level comments, but I'm wondering about a few things.

First off, and I guess the most important bit, is how you're planning
to deal with the C++ cast/declaration ambiguity.  This ambiguity
affects a lot of the places which are testing ahead for a type, so
adding code that's looking ahead only as far as the end of the type
seems like a temporary step at best.  I'm not saying that this patch
is necessarily the wrong way to go (I really have no clue how I'd go
about implementing the ambiguity resolution performantly), but I want
to make sure you have the next step planned so that you don't end up
making extra work for yourself.

This is a more of a side-issue, but would it be worthwhile to make the
parser keep track of enough information to implement  isTypeName
itself?  It's a relatively large burden on anyone who wants to write
an Action implementation to be required to keep track of enough
information to figure out the answer to this question, especially for
C++, and having the parser use different implementations of identifier
resolution depending on whether we're using Sema or not seems bad.
The obvious arguments against this are that it's sort of duplicating
code from Sema, and it might affect performance for the normal case of
using Sema.  That said, it seems worth considering anyway if we really
expect people to be writing their own Action implementations.


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